Fat Bear Week has been an annual event for the past five years in Katmai National Park and Preserve in southwestern Alaska. The idea is to publicize and celebrate the process of bears eating as much as they can to build up crucial fat reserves in advance of winter hibernation.

Park rangers made a game out of the process — a March Madness-style bracket matching bear against bear, each with photos proving girth and inviting the public to vote on the fattest bear in each pair.

The winners move on to the next round; the losers are out.

This year's championship round pitted Holly against No. 775, Lefty.

And in the end, it was no contest.

After 12 hours of online voting, Holly had about 17,500 votes, while Lefty had about 3,600.

"It was very hard to get a good picture [of Holly] out of the water," she says, "because she was a submarine for the entire month. She did not stop fishing, except to dig a belly hole big enough for her to sleep in."

Holly and all of this year's 12 contestants are coastal brown bears that forage along the Brooks River. The Alaskan waterway has one of the largest concentrations of sockeye salmon in the world, and the bears there take full advantage.

This year's weeklong competition was a huge success, with a record total of 187,000 votes cast — more than three times last year's total.

Along with the novelty and fun of the event, Boak and her fellow Katmai Conservancy media ranger Brooklyn White hope it builds awareness of a natural process and the need to conserve the unique wilderness area of the Brooks River.

"Not all bears have this same kind of access to these salmon resources," White says, "and to an ecosystem that has such clean water."

White says many ecosystems, even within Katmai, are breaking down, caused by human encroachment to warming temperatures that are putting salmon under "heat duress."

"Because of the drought, the salmon were really delayed" in reaching the Brooks River," Boak says. "[T]hey stayed in small creeks and streams that were very dry."

She says the bears stayed around those streams because of the easy fishing and didn't arrive at the Brooks until mid-September. Normally they're there, gorging on salmon around the first of the month.

Because of the delay, Boak says the fat bears in this year's competition are still eating and will continue doing so right up until late this month, or early November, when hibernation usually begins.

And when it does, it's not — as many think — as simple as the animals merely going to sleep.

"[Hibernation] is a reduction in their metabolic rate," says White, who's worked on the Brooks River the past four years. "[The bear's] heart rate lowers, the activity obviously is very minimal and it truly is just their body utilizing that fat to keep this baseline going."

If the bears don't have adequate fat stored, some may even die during hibernation, Boak says.

That's why the fattest bears have the best chance at survival. When spring rolls around, they'll be able to emerge from their dens to continue their life cycle.